1. Field of the Invention
This invention relates to a camera control system for automatically controlling the charging of an electronic flash and, more particularly, to a camera control system for automatically controlling the charging of an electronic flash as a function of readying the camera in anticipation to implementing a photographic exposure cycle and as a function of actually initiating the photographic exposure cycle.
2. Description of the Prior Art
Fully automatic cameras for use with instant film capable of being folded into a thin, compact shape suitable for convenient carrying in the pocket of a garment are well known in the art as evidenced by the Polaroid SX-70 Land camera, made and sold by the Polaroid Corporation of Cambridge, Mass., U.S.A. Cameras of this type are intended to be used with well-known instant developing film cassettes which include an integral power supply. The power supply, forming an integral part of the cassette, is a battery which supplies electrical energy for the operation of components of the camera in which the film units are exposed and processed. The camera includes various subsystems which, for example, may include an exposure control system, a film transport system, a dark slide removal system, a motor-powered mechanism for processing an exposed film unit, and electronic logic circuits that provide a sequenced control function.
In addition, it would be highly desirable to power an electronic flash from the film cassette battery as is described in U.S. Pat. No. 4,074,295, entitled "Compact Accessory Strobe for Cameras with Battery Enclosed Film Pack," by Richard C. Kee, issued February 14, 1978, or U.S. Pat. No. 4,231,645, entitled "Camera with Telescoping Dual Actuators," by Carl W. Davis et al., issued Nov. 4, 1980, in common assignment herewith. However, powering both the camera electronic systems including the camera motor drive as well as the electronic flash presents a high power drain to the battery which could potentially result in battery failure prior to the exposure of all the film units in the film cassette. Such a battery failure would become likely if the user should turn on the flash and leave it to operate in a continuous charging mode over an extended period of time.
In order to inhibit the user from doing this, there may be provided a dual actuator system as disclosed in U.S. Pat. No. 4,231,645, supra, in which the electronic flash is energized to charge upon actuation of a first button in a dual telescoping button arrangement which is utilized to commence the exposure cycle. Thus, only when the user is ready to actuate the camera to initiate the photographic exposure cycle is the flash charged as a preliminary step to the actuation of the camera thereby eliminating the possibility that the electronic flash might be left in its charging mode of operation over an extended period of time. However, the aforementioned arrangement requires that the flash be charged from a fully discharged condition during this preliminary step in the actuation of the photographic exposure cycle thereby delaying the commencement of the exposure interval by that time required to apply the entire charge to the flash capacitor.
Therefore, it is a primary object of this invention to provide a control system for automatically controlling the charging of an electronic flash in a manner minimizing the power drain from the battery without requiring the entire charging operation to occur as a preliminary step in the actuation of a photographic exposure cycle.
It is a further object of this invention to provide a control system for automatically controlling the charging of an electronic flash as a function of either readying the camera in anticipation to implementing a photographic exposure cycle or as a preliminary step in the actuation of the photographic cycle.
Other objects of the invention will in part be obvious and will in part appear hereinafter. The invention accordingly comprises the mechanism and system possessing the construction, the combination of elements and the arrangement of parts which are exemplified in the following detailed disclosure.